Sauna does not work i think it is the controler

My sauna is having the same error, did you find a solution?

When I'm in a traditional sauna like this, I expect the temperature to be between 70 and 90C so that's what I assume you are trying to reach. There could be several reasons for this so make sure each point is checked:
1. Stating the obvious, to increase the temperature inside the sauna, you'll have to ladle water onto the hot sauna stones.
2. Maybe the insulation within your sauna isn't good enough and heat is escaping.
3. Your sauna room could be too big for this heater to heat properly.
4. Maybe the element on the heater isn't performing properly and needs to be replaced.

These were some pointers which Di Vapor gave as possible reasons for lack of heat.
Sauna Electric Heaters Spares

Can you provide more detail on the manufacturer and model number?

I think you have the wrong category.

On top of the unit/sauna, you will need to remove the roof or wood covering. It is held down with screws, usually. If your unit in fact does have a reset it will be located on the side of the control box which is located on top of the sauna.

Did you get an answer to your question. I am also looking for s126smd3 to buy.

Unless you have "Nordic Mini 3" for 240 V, all other types of Nordic sauna are more than 5000 Watt which means that their rated current for 240V is more than 30 A. For 120V it is two times more.

I don't know your type of Nordic, the rating of the fuse and what voltage are you using, but it may be less than the needed rating. Check the rated voltage and current of your sauna heater.

If your voltage is equal to the rated and the rated current of the sauna heater is less than the rating of the blown fuse, you may have short in a part of the heater.